1. Technical Field
The present invention relates to a resonator device, an oscillator, an electronic apparatus, and a vehicle.
2. Related Art
In the communication equipment field, there has been used a resonator device such as a quartz crystal resonator or a quartz crystal oscillator, which uses a resonator element formed of a piezoelectric material such as quartz crystal to output a signal with a desired frequency, in order to obtain a signal with a stable frequency. As described in, for example, JP-A-2014-86842, there has been disclosed a configuration of providing a mound to an electrode pad in a container to stably ensure the thickness of an electrically-conductive adhesive in a resonator device having a resonator element supported by a connection pad so as to form a cantilever. In this configuration, there is disclosed a resonator device capable of reducing a variation of the frequency characteristic of the resonator device, for example, a so-called hysteresis affecting the reproducibility of the frequency variation with respect to the temperature change, by making the heat to be transferred from the outside of the container to the resonator element via the electrically-conductive adhesive hard to be transferred to thereby decrease the temperature gradient in the resonator element.
However, in the resonator device shown in JP-A-2014-86842, the hysteresis as the variation of the frequency characteristic of the resonator device varies due to the stress applied to the resonator element due to a change in ambient temperature of the resonator device besides the heat transferred from the outside of the container. The stress applied to the resonator element due to the change in ambient temperature of the resonator device is also affected by a distance between connection members for connecting the resonator element and the container to each other, and a positional relationship between the connection members and excitation electrodes of the resonator element. Further, it results that the smaller in size the resonator element is made in order to apply the resonator element to a resonator device smaller in size, the more significantly the stress is affected by the distance between the connection members and the positional relationship between the connection members and the excitation electrodes of the resonator element. For example, it is conceivable that the hysteresis in such a small-sized resonator element as having a size (length) in the direction, in which the connection members are arranged, of no larger than 1.5 mm is significantly affected by the positional relationship between the excitation electrodes and the connection members, the material (linear expansion coefficient) of the excitation electrodes, and so on. Therefore, only by stably ensuring the thickness of the electrically-conductive adhesive for connecting the container and the resonator element to each other as in the resonator device of JP-A-2014-86842, there is a possibility that the characteristic variation, for example, the hysteresis or the like of the resonator device becomes large.